Technical guidelines on design, construction and maintenance of twin pit pour flush latrines

 72042 TECHNICAL GUIDELINES ON Tvvin Pit Pour Flush Latrines -- Ministry of Urban Development Govt. of India Regional Water & Sanitation Group - South Asia UNDP I World Bank Water & Sanitation Program I~ Technical Guidelines on f Design, Construction and Maintenance of Twin Pit Pour Flush Latrines Ministry of Urban Development Regional Water &Sanitation Group-SouthAsI.. Govt. of India UNDP/World Bank Water & Sanitation Program  mnr m<m ~ T<t<ti1(1 4i'''Ilt'1<4 GOVT. OF INDIA I\IlNISTRY Or- URnAN DEVELOPMENT ;rf ~ - 110011. orilu- 1992 ~ I)aud N/,II' Orllli-IIM.II rlIC 28th April, 1992 SECRETARY FOREWORD The most appropriate technology is that which provides the most socially and environmentally acceptable level of service at the least economic cost. The low cost sanitation scheme using twin pit pour flush latrine is no exception. In view of the constraints of resources and water scarcity and also to better environmental conditions by sanitary disposal of human excreta, the low cost sanitation programme is a useful alternative to achieve the objective. The Government of India has launched an Integrated Low Cost Sanitation Scheme under the Liberation of Scavenger Programme wherein it has been proposed to provide low cost sanitation latrines on "whole town" basis to the 500 towns every year, having a population less than 51akhs during the Eighth Five Year Plan (1992-97). This gigantic task needs concerted efforts and close collaboration of a Group of Engineers, Social Scientists and Community Development Workers to achieve more effe·ctive results under this programme. The technical guidelines prepared by RWSG -SA, UN D P / World Ban k Water and San itati on Program wi II no doubt serve the programme implementors to a great extent. These guidelines have been preparedin a very systematic and objective manner so as to construct the low cost sanitation latrine without much of probJems under different geographical and hydrological conditions. The approach adopted in these guidelines is very well understood even by beginners with little knowledge and training on low cost sanitation. I hope that these technical guidelines will serve as an effective tool for the implementing authorities and will be used by them extensively for effective and eWcient outcome of the programme of Government of India.  CONTENTS 1. Why Guidelines? 1 2. What is Twin Pit Pour Flush Latrine? 2 Drawing: Squatting Pan and Trap for Pour Flush Latrine 3 3. How to Design Leach Pits? 4 Sludge Storage Volume 4 Infiltration area 5 Pits in Water Logged, Flood Prone and High Sub Soil Water Areas 5 Drawing: Pour Flush Latrine in Waterlogged Area 6 Drawing: Pour Flush Latrine in High Sub-Soil Water Area 7 Pits in Snow Region 8 Pits in Rocky Strata 8 Pits in Soils with Low Infiltration Capacity 8 Pits Where Space is a Constr~int 8 Drawing: Pour Flush Latrine with Combined Leach Pits 9 Size of Leach Pits 10 Shape of Pits 10 Location and Orientation of Pits 10 Spacing between Two Pits 10 Precautions 10 4. How to Construct Pour Flush Latrines? 11 Latrine Cubicle 11 Squatting Pan and Trap 11 Foot rests 11 Pit Lining 11 Pit Bottom 12 Distance of the Pits from Foundation 12 Pit Cover 12 Interconnection Between Pits and Squatting Pan 13 Latrine Superstructure 13 Drawing: Pit Lining with Dry RR Stone Masonry 14 Drawing: R.C.C. Coverfor Leach Pits 15 Drawing: Junction Chamber and Brick Drain 16 5. What are the Pollution Safeguards? 17 Drawing: Leach Pits with Sand Envelope 18 6. How to Operate and Maintain a TPPF Latrine? 19 Diversion of Flowfrom One Pit to Another 19 Removal & Disposal of Pit Sludge 19 Do's 19 Dont's 20 7. What should the Supervisor Check during Construction? 21  List of Annexes Annex 1. Pour Flush Latrine with Dry Circular Leach Pits Size of Pits and Material Required for Construction 24 Annex 2. Drawing: Pour Flush Latrine with Dry Circular Pits 25 Annex 3. Pour Flush Latrine with Wet Circular Leach Pits Size of Pits and Material Required for Construction 26 Annex 4. Drawing: Pour Flush Latrine with Wet Circular Pits 27 Annex 5. Bill of Quantities for Pour Flush Latrine with Dry and Wet Circular Leach Pits 28  Why Guidelines? Conventional water flush toilets are normally flushed with 10-14 litres of water from a cistern attached to it. In a Pour Flush (PF) latrine, as the name suggests, the excreta is "hand" flushed by pouring about 1.5 to 2 litres of water into the pan. In relation to conventional sewerage or septic tank, the PF latrine is a low cost sanitation syste~. A manual on the Design, Construction and Maintenance of Pour Flush Latrines (TAG Technical Note No.1 0) was published by the World Bank in 1984. Since then hundreds of thousands of PF latrines have been constructed allover India and in many other developing countries under different physical, geological and hydrogeological conditions. The Government of India has launched a massive programme to improve sanitation in urban and rural areas. It is difficult for field staff involved in these programmes to refer to a voluminous manual for day-to-day activities. Hence these Technical Guidelines have been prepared, covering the essential features of PF technology and the latest design improvements, based on past experiences. This is primarily meant for the ready reference of field staff on design, construction and maintenance of PF latrines. 1  What is Twin Pit Pour Flush Latrine? Components The PF latrine consists of a. asquatting pan of special design (Drawing on page 3) set on the floor; b. a trap with a 20mm waterseal, to prevent the emission of foul smell and fly / mosquito nuisance (Drawi ng on page 3) ; c. two leaching pits which retain solid matter and allow liquid to leach and gases to disperse into the ground; and d. an interconnecting system between pits and trap. e. a superstructure. Functioning The excreta is carried into subsurface leach pits through pipes or covered drains and one pit is used at a time. The liquid infiltrates into the soil through the holes in the pit lining. The gases also disperse into the soil, and therefore, the provision of a vent pipe for its outlet is not necessary. When one pit is full, the excreta is diverted to the second pit. The filled pit can be conveniently emptied after a rest period of one and a half years, ~ during which pathogens are inactivated and the organic matter decomposed. Thus the two pits can be used alternately and continuously. In a single pit system desludging is required immediately after the pit has .filled up, and therefore involves handling of fresh and undigested excreta which is hazardous to health. Single leach pits are appropriate only if a mechanical desludging vacuum tanker is readily available, or if the pit is abandoned when full. 2  / . ..0 .,,­ ! ~.~' ~ . - . -. Scole: 1:5 -~·-·-·-·-·-·-·1ig-·-·-·-·-·-·-·-·-·-·-~ I -+2-' - ' - '- ' - ' -'- ' - '- ' -'- ' - ' -' -'- ' -'- ' ~ I ...... ~ -.­ 70 i ! I I i i i oi ~i I i i i i ~ ....Z._ ... DIA SECTION A-B SQUATIING PAN Scole: 1:7.5 All dimensions in mm SQUATTING PAN AND TRAP FOR POUR FLUSH LATRINE 3  How to Design Leach Pits? The size of the leach pits is determined first has to be increased to prevent flooding due on the basis of the volume required for to surcharge. For designing pits, the volume storage of solid matter, and then it is checked needed per person per year is given below: whether it provides sufficient infiltrative surface area for infiltrating waste water to Table - 1 the surrounding soil. If it does not, the volume Pit Design-Volume Per Capita Per Year in cubic metres should be increased to provide adequate infiltrative surface area. A free space of at . + least 300 mm must be provided above the Material used Dry pits Wet Pits invert level of the inlet pipes or drains up to for anal cleansing (2 year desludglng the bottom of the pit cover. Interval) Sludge Storage Volume Water 0.078 The volume required is calculated on the basis of sludge accumulation rate, the number . + Soft paper 0 .053 0.104 of persons likely to use the latrine, and the deSign sludge storage period. Other anal cleansing materials such as hard Storage Sludge accumulation paper, leaves, mud balls, corn cobs, etc. are volume = rate X Number of users unsuitable for use with PF latrines as they needed X Design storage period block the trap and the interconnecting pipes or drains. SLUDGE ACCUMULATION RATE NUMBER OF USERS A leach pit is classitied as wet or dry depending on whether the ground water table The number of persons likely to use the latrJne is above or belowthe bottom of the pit. I n dry varies from house-to-house, but to standardize pits the storage volume needed is calculated construction details, pits are designed for 5, 10 only on the basis of sludge accumulation and 15 users. If the users in the household are rate. But in wet pits even though the sludge more than 15, it is better to provide two pairs of accumulation rate is lower, the pit volume pits of appropriate size. ,. Source: Report of the Committee on Design Criteria for Pour Flush Waterseal Latrines in Rural Communities of India - The Technology Advisory Group-India, March 1985, and Appropriate Sanitation Alternatives - A Planning and Design Manual by John M. Kalbermatten & others - World Bank Studies in Water Supply and Sanitatio'!. + For soft paper to be used for anal cleansing and wet pits, volume has been increased in the same proportion as in 'The Design of Pour Flush Latrines' by Duncan Mara - Technical Note No. 15. 4  STORAGE PERIOD Table - 2 Long Term Infiltration Rates for Different Soli The minimum design interval between Types* successive manual desludging of pits could be one and a half years which is the period Soil type Lltres per m2per day required for inactivation of the most· persistent pathogen present in faecal matter SMd 00 (ascaris ova). To allow for a reasonable Sandy loam. loams 30 degree of operational flexibility as well as to Porous silty loams. porous silty provide a safety factor. it is desirable to clay loams 20 provide at least 2 year storage volume. Compact silty loams. compact silty clay loams. clay 10 However. if necessary. the pits can be ~ designed for longer periods. FLOW TO THE PIT Infiltration Area Unless more specific data is available. flow The area required for infiltration is calculated to the pit is taken as 9.5 litres* per day per by taking into account the expected total person . This includes urine. excreta. and daily flow to the pit and the long term water used for anal cleansing after infiltration rate of the soil where the pits are to be located. defecation and flushing. The total flow in the pit is calculated by multiplying the expected number of latrine users by 9.5 and adding Infiltrative Daily total flow to the pit 5 litres + for the water used for washing and surface area = cleaning the latrine floor and squatting pan. required Long term infiltration rate of soil Pits in Water Logged, Flood Prone and High Sub-soil Water Areas The vertical surface area of the soil in contact with the pit walls from the pit bottom to the In high sub-soil. water log,ged or flood prone invert level of the pipe or drain is to be areas. the pits should be raised above the considered for infiltration. The bottom ofthe ground level to a height such that the invert of pit is not taken into account for infiltration as the incoming drains/pipes is just above the it clogs in the course of time . likely flood water or sub-soil water level. Raising the pipes will necessitate raising LONG TERM INFILTRATION RATE the latrine floor also. The infiltration rate for different types of soil I n pits located in water logged or flood prone is taken to calculate the infiltrative surface areas. earth should be filled and well area required as shown in Table 2: com pacted all around the pits in 1000 mm width and up to the top (Drawing on page 6) . It is not necessary to raise the pits by more * Source: The Design of Pour Flush Latrines by D. Duncan Mara - TAG Technical Note No. 15. + Source: Report of the Committee on Design Cnteria for Pour Flush Waterseal Latrines in Rural Communities of India. The Technology Advisory Group - India, March 1985. 5  lHICK CEWENT CONCRETE 1:2:4 OVER THICK CENEN'T CONCRETE 1:8:12 #lD FINISHED SWOOTH BY CEWENT PUNNING FOOT RESTS DlA A.c. OR P.V.C. PRE:SSUI'l£ PIPE r'...'.".:...... 1:2:4 WORK IN CD.lENT WORTAR 1:8 HONEYCOWBING IN ALTERNA"T£ lAYERS I i i ...... 225 SECTION A-8-C ....... 2 25 ~ . -. -D-·-· -· -· ~l-· -~~~·-· -t· - - --r-'!--­ - --­ ovn..£T TO BE OPENED .o.L _of"'I---,-115 Scale: 1:50 All dimensions in mm POUR FLUSH LATRINE IN WATER LOGGED AREAS 6  'THICk CEMDlT CON~ 1:2:4 OYER TllICI( ca.lDlT CONCRETE1:e: 12 AND ANISHED SUOOTH BY CEiolENT PUNNING FOOT RESTS .------AIN~nON ~B~ 75mm 011'< A.c. OR P.V.C. NON PRESSURE ~PE rl<.l';""":>I.JUI 1:2:4 ~!:~-,2~-­ l00-+­ . ....... calENT CONCRETE ';8;12 225 75 EAKIli AWNG - - - - - - - ' WORk IN C9AENT MORTAR 1:6 HONEYCOMBING IN AL1<RN.l.TE lAYERS i i 225 225~ +-.-+ +-.-+ SECTION A-8-C lUI 11' -Ftt_ ·_· _· E·_·_·-·ii~t­ NOTE:- WAlCR TASI..£ LESS THAN 300mm BEl..OW GROUNO LEVEl. Scale: 1:50 All dimensions in mm POUR FLUSH LATRINE IN HIGH SUB-SOIL WATER AREA 7 than 300 mm (free space as specified in Pits in Soils with Low Infiltration page 4) above the plinth of the house Capacity because if water rises above the plinth, the residents wilranyway vacate the house. Leaching capacity tends to be the limiting In high sub-soil water areas, about 300 mm factor when the infiltrative capacity of soil is filling all around the pits may be done low. In these circumstances, there are two depending on site conditions (Drawing on options: construct a larger pit, or increase page 7). the critical leaching area. The former option is costly, while the latter can be In these situations, the pits should be accomplished by backfilling and compacting desi gn ed as wet pits, taki n g into with brick ballast, gravel, sand etc., in the r consideration the infiltration rate of the type required width all around the pit, since the of soil. leaching area is the vertical surface of the excavation of the pit rather than the external wall of the pit (See page 5 under "Infiltration Pits in Snow Region Area"). Experience has shown that PF latrines with Pits in Black Cotton Soil are designed twin pits function satisfactorily in areas on the basis of whether the pit is wet or subjected to snow fall in winter. The pits can dry, taking the infiltration rate as 10 litres be designed on the same considerations per sq . metre per day. However, a minimum as those in the plains and should be 300 mm* vertical fill (envelope all around constructed below the frost line. the pit) of sand, gravel or ballast of small Pits in Rocky Strata sizes should be provided all round the pit, outside the pit lining, to separate the soil In rocky strata with soil layers in between, and the pit lining as well as to increase the leach pits are designed on the same infiltrative surface area. principles as those for low sub-soil water level taking the long term infiltration capacity Pits Where Space is a Constraint of the soil as 20 litres per sq.m per day . . However, io n rocks with fissures, chalk Where circular pits of standard sizes cannot formations, or old root channels, pollution be constructed due to space con strai nt, can flow over a very long distance; hence deeper pits with smaller diameter (not less the s e co n d it ion s d e man d car e f u I then 750 mm), or combine d 0val, square or investigation and adoption of poll uti on rectangular pits divided into two eq ual . safeguards (See page17) . compartments by a partition wall, may be provided. In case of combined pits, the In impervious rocky strata, since there will partition wall , as well as the adjoining side be no infiltration of liquid, the pits will function walls up to 225 mm width, should not have as holding tanks. In such situations, a PF any holes. The partition wall should be 225 latrine w~th I~aching pits is not a suitable mm deeper than the pit lining. Both faces of system. the partition wall should be plastered in cement mortar 1 :6 (Drawing on page 9). *'Source: Final Report on Low Cost Waterseal Latrines in Urban Community by the Central Building Research Institute Roorkee (India) - October 1980 - Study carried out under the UNOP Global Project GL0/78/006. • B  r - - - EARtH FlWNG ....-_ _-11 TOP Of" PIT UNING PlASlERED CEMENT MORTAR 1:6 fRoC.C.sLAS 1:2:4 GROUND ' . . ': •. .. ', ., ...... .' ,' :. : : . : .."': " , : •.....:..' :':." "._ ~... YftL Q~ ~ - ~T ~ ~ CEMENT MORTM 1:6 11Smm THICK BRIO< WORK IN CEMENT MORTAR 1:8 WITH HONEYCOIoABING IN AllERNAlt BRICK COURSES 0 NO HOLES IN PAR1Tl1ON WAU. AND IN PIT UNING UP TO 225mm WIDTH ADJOINING lliE PNrnTlON WALl. 225 .....-+ SECTION A-8 NOTE:­ lli E SIZE Of" HOLES IN HoNEY'COWBI NG SHOUD BE ..,~ 50mm WIDE AND FUll HEIGHT Of" BRICK COURSE. ::~ IN SoINDY SOIL OR WHERE 1l£RE ARE CIWlCES OF IWoWlE BY FIELD RA~ OR WHERE SAND EIMI...OPE IS PROIIIDED. i WIDTH OF HOLES BE REDUCED TO 12 TO 15mm i 1 j 1 .Jj I THIO< ce.tENT PlASlER IN 1:8 BOTH FACES OF PNmTlON WAll OunET TO BE OPENED AllERNATEl..Y ..,--.­ ::-.­ ·1 "'-++~-j---+!'-" l Scale: 1:50 All dimensions in mm POUR FLUSH LATRINE WITH COMBINED LEACH PITS 9 Size of Leach Pits located under the street orfoot path. In such cases, the pit cover should be designed to The sizes of pits have been worked out for 5, withstand the expected load which it will be 10 and 15 users (see page 4 under "No. of subjected to. Users") assuming ! Ideally, the pits should be placed a. 2 year desludging interval (see page 4 symmetrically at the back of the squatting under "Storage Period"); pan, as shown in the drawings on pages? and 9. If site conditions do not permit this lay b. volumeneeded for dry pits 0.04m 3/cap/yr out, the pits can be located in any angle as and for wet pits O. 0?8m 3/cap/yr (see page long as drains/pipes are straight, are 4 under "Sludge Storage Volume"), properly sloped with a minimum gradient of 1: 15 and have no sharp bends. c. hydraulic loading 9.5 I/cap/day plus 5 litres for washing latrine floor (see page Spacing Between Two Pits 5 under "Flow to the Pit"); and The space between the two pits* should be d. long term infiltration rate of soil 10, 20, at least the effective depth + of the pit. If the 30 and 50 l/m2/day. spacing has to be reduced, an impervious barrier such as a cut-off screen or puddle The sizes worked out are given in Annex1 clay wall should be provided between them. and Annex 3 (see page 24 and 26). Precautions The depths given in the tables are effective depths measured from the invert of pipes or Wherever found necessary, the design drains to the bottom of the pit. The total should make provision for safeguards to depth of the pit would be 300mm more than prevent pollution of drinking water sources the depths specified in the tables, to allow as specified on page 1? for free space. Shape of Pits Wherever possible circular pits should be constructed because of their structural strength and relative larger surface area. Location and Orientation of Pits The pits, as far as possible, should be located within the premises of the house. However, if this is not possible, they can be ,. Source: Manual on the Design, Construction and Maintenance of Low Cost Pour Flush Waterseal Latrines in India - TAG Technical Note No. 10; and The Design of Pour Flush Latrines by D. Duncan Mara - TAG Technical Note No. 15. +Effective depth is the depth of pit below invert of pipes or drains to bottom of pit. 10  How to construct Pour Flush Latrines? Latrine Cubicle to ensure a 20mm waterseal. While fixing the trap, keep the top of the inlet and the top The minimum internal size* of the latrine curvature of the trap horizontal; the squatting cubicle should be 750 mm from side to side pan should then be fixed over the trap in and 900 mm from front to back. In firm soil such a way that its rim is horizontal andflush the depth of the foundation should be as with the latrine floor. This process will ensure shown in drawings on pages 25 and 27. In 20 mm waterseal in the trap. The distance loose or filled up or black cotton soil, the between the pan and the back wall of the foundation should be designed as per site latrine superstructure should be ' about conditions. The plinth should be a minimum 200 mm. of 225 mm above ground level. Footrests Squatting Pan and Trap These can be of ceramic, cement concrete, The pan could be of Ceramic, Glassfibre cement mosaic or plastered brick. The top Reinforced Plasfics (G RP), Cement of the foot-rests should be about 20 mm Concrete (CC), Cement Mosaic, Poly above the floor level and inclined slightly Propylene (PP) or Poly Vinyl Chloride (PVC). away from the squatting pan in the front. Ceramic pans are the best but costliest. Alternately foot rests can be an integral part Mosaic or cement concrete pans have the of plastic or ceramic squatting pans. advantage that they can be manufactured locally by trained masons, butthey are heavy Pit Lining and the surface tends to become roug.h after long use. Their acceptance is lower than BRICK LINING other types. The pits should be lined to avoid collapsing. Traps for ceramic pans are made of the Bricks jointed in 1:6 cement mortar are same material but for GRP pans, High most commonly used for lining. The thickness Density Poly Ethylene (HOPE) traps are of the brick lining could be 75 mm, but due used. For mosaic and cement concrete pans, to poor acceptance and difficulty in traps are 'of cement concrete. construction, the lining is generally made · 115 mm thick . The rim of the squatting pan should be installed horizontally and the trap connected .. Source: Manual on the Design, Construction and Maintenance ofLow Cost Pour Flush Waterseal Latrines in India - TAG Technical Note No. 10. 11 SIZE OF HOLES IN BRICK LINING BURNT CLAY RINGS The lining in the brick work should be by Where available, burnt clay rings of uniform honey-combing up to the invert level of the deep cherry red or copper colour with holes incoming pipe or drain. The size of the holes can also be used for lining pits where they should be about 50 mm wide, and extend to are not subjected to heavy pressures of the full height of the brick course. For simpler loading. construction, holes should be provided in alternate brick courses. If the soil is sandy or STONE LINING a sand envelope is provided or there are chances of damage by field rats, the width of Stones or laterite bricks could also be used the openings should be reduced to 12 to 15 depending upon their availability and cost. mm (Drawing on page 18). Where the Lining can be constructed in random rubble foundation of a-building is close to the pit, stone open jointed pitching (no mortar) with holes should not be made in the portion of one layer at the bottom and the other in the lining facing the foundation. However while middle, in cement mortar 1:6 (Drawing on designing pits in such a situation, the page 14). infiltrative area should be increased because less surface area would be Pit Bottom available for infiltration due to brick work without holes. The lining above the invert of Except where precautions are to be taken to the pipes or dra~ns, up to the bottom of the prevent pollution of drinking water sources pit cover, should be in solid brick work, i.e. (see page 17). the pit bottom should be left with no openings. in a natural condition. CEMENT CONCRETE RING LINING Distance of Pits from Foundation+ The concrete rings used for lining should be Pits up to 1.7 m depth can be safely located 40 mm thick, about 300 mm in height and at a distance of 500 mm from the existing constructed with 1:3:6 cement concrete, structure (distance between the foundation einforced with 2 rings of 6 mm dia mild steel r_ of the building to periphery of pit). For 2 m bars. The first ring is placed after casting 50 deep pits; a safe distance is 900 mm. mm of height and the second ring is placed at a height of 250 mm. Each ring should have Pit Cover two rows of 50 mm circular holes staggered about 200 mm apart. The rings are not to be Usually Reinforced Cement Concrete (RCG) jOinted with mortar but are put one over the 1 :2:4 slabs are used for covering the pits, other. Below the pit cover two courses of but depending upon the availability and cost, brick work in cement mortar 1 :6 should be flagstones can also be used. The RCC provided for supporting the pit cover. The slabs may be cast in two pieces for use of concrete rings is advantageous in the convenience of handling. The thickness of a construction of wet pits. RCC pit cover will depend upon the load +Source: Final Report on Low Cost Waterseal Latrines in Urban Community by the Central Building Research Institute, Roorkee (India) - October 1980 - Study carried out under the UNDP Global Project GL0/78/006. 12  expected to come on it. For pits located i. White or colour washed jute, or thick inside the premises ofthe household, where plastic sheet enclosures on a bamboo they are not subjected to heavy loading, the frame; thickness can be 50 mm but in such cases the covers should be centrally cast with stone ii. Mud walls with a thatched or tiled roof; ballast to ensure quality control. Brick ballast (of overburnt or first class bricks) can be iii. Date palm or bamboo matting with used where stone ballast is not easily bamboo frame and a thatched or tiled available and is costly, but the thickness of roof; the slab should be increased to 75 mm . iv. In the hills, walls of slates or small stone The details of reinforcement in RGG pit pieces and a roof of slates. covers are shown in the drawing on page 15. It is advisable to provide a superstructure Interconnection Between Pits and along with the latrine substructure to ensure r Squatting Pan its immediate use. The trap is connected to the pit through a 75 mm brick channel of 'U' cross sectional shape covered with bricks jointed with weak mortar (for example mud) or cement mortar 1:12 (Drawing on page 16), or 75 mm dia A.G ., or PVG non pressure pipe. In case pipes are used, a chamber of minimum size 250 mm x 250 mm (Drawing on page 16) should be provided at the bifurcation point to facilitate cleaning arid allowing flow to the pit. In the case of a drain, the 'Y' portion of the drain serves the same purpose. The channel or pipe should have a minimum gradient of 1 : 15. The pipe or drain leading to the pit not in use should be completely sealed with a temporary plug, say of brick, stone or concrete etc., joined with weak mortar. Latrine Superstructure The superstructure should be designed to ensure privacy, convenience, comfort and easy maintenance. It should be well ventilated. It can be any of the following types in the case of a brick or concrete superstructure being unaffordable: 13  E:ARTH FlWNG RANDOU RUBBI.£ (RR) STONE t.tASONRY ' - - - - - i IN CE~ENT ~ORTAR 1:6 i :I:!I RANOoM RUBBLE (RR) STONE OPEN JOINnD PITCHING WIT}! ONE LA'IER AT BUTTOIo4 AND OT11ER IN MIDQt.£ IN CEMENT NORTAR 1:8 I. ' - -_ _-lONE COURSE OF RANDOM RUBBLE (RR) STONE MASoNRY IN CEMENT MORTAR 1:6 SECTION A-B THICKNESS NORMALLV 300mm 75mm DIA PIPE FRO~ JUNCTION CHAIoIBER - - - - - ' Scale: N.T.S. All dimensions in mm PIT LINING WITH DRY RR STONE MASONRY 14  BAR SCHEDULE FOR ONE HALF COVER DIA OF NO OF BARS SLAB LEACH PIT 10) HORIZONTAL VERTICAL THICKNESS 900 8 4 50 1200 10 5 60 1400 12 6 75 r---- SEE DETAIL X 6mm 1& BARS 0 150 c/c BOTHWAYS gt~~~~~~~~ t· ~~~ . --- . ~ . --- . --- . ~ DETAIL X SECTION A-8 6mm JII BARS 0 150 c/c BOTHWAYS I --­ .1 / / / ,, , -­ -­ NOTE:­ COVER TO BE CAST IN 1WO SEMICIRCULAR HALVES Scale: 1:20 All dimensions in mm RCC COVER FOR LEACH PITS 15  ,-------SLOPE 1:10 -+­ III I "i -,­ i i o· Ill ' ~I 1111 =t­ <'<.:' ~ . -j ~>:.~ oO ' "I -+­ 12 '12 83 W 75 83 -f · -ff-·-·+t-·~- +.-.U·~-·-·-·~~·-·-·-tJ·llI·-·+ 25mmCC 225 -+-.-.-.- .- . -. ~.- . -.-.-. - .- .-.-+- 1:2:4 ANISHED -t·-·- · -·-·-·-·~- SMOOTH ;_._._._._._·_·-t 24-9 SECTION A-B SECTION A-B TO lEACH PIT( \ TO lDoCH PIT - ·-·.!~~t-·-·-·-~~-·-·-t~~~-·-t-·- -t·-·-·-·-·-~- ·-·-·-·-·-·-·-·-t·- .E..l.Afj \ TO L.EN:H PIT JUNCTION CHAMBER BRICK DRAIN Scale: 1:10 All dimensions in mm JUNCTION CHAMBER AND BRICK DRAIN 16  What are the Pollution Safeguards? Proper information and investigation of both as specified above can be maintained geological/hydrogeological conditions of by providing a 500 mm thick sand sites where pits are to be located, and the envelope, of fine sand of 0.2 mm location of drinking water sources,size, all effective size, all around the pit, and are pre-requisites in planning, designing and sealing the bottom of the pit with an construction of on-site low cost sanitation impervious material such as puddle systems to ensure that pollution risk to clay, a plastic sheet, lean cement ground water and water distribution mains is concrete, or cement stabilised soil (for minimal. Faulty construction and wrong data! sand envelope see Drawing on page information regarding hydrogeological 18). conditions may lead to pollution of drinking water sou rces . d. If the pits are located under a footpath or a road, or if a water supply main is To ensure that the risk of polluting ground within a distance of 3 m from the pits , water and drinking water sources is minimal, the invert level of the pipes or drains the following safeguards should be taken connecting the leach pits should . be while locating the pits: kept below the level of the water main , or 1 m below the ground level. If this is. a. Drinking water should be obtained from not possible due to site considerations, another source or from the same the joints of the water main should be aquifer but at a pOint beyond the reach encased in concrete. of any faecal pollution from the leach pits. b. If the soil is fine (effective size 0.2 mm or less). the pits can be located at a minimum distance of 3 m from the drinking water sources, provided the maximum ground water level throughout the year is 2 m or more below the pit bottom (low water table). If the water table is higher, i.e. less than 2 m below the pit bottom, the safe distance should be increased to 10m. c. Ifthe soil is coarse (effective size more than 0.2 mm), the same safe distances 17  C.C.S1AB 1:2:4 ," JIt, • - ," •• --' ' , " ... . . , '. ..... . '.:. .: : : .:: : '. ... •': •• . !WID ENVEI..OPE wmi ... . . ' ., . . '......~---='-----I CI.2mm SAND : : ...... ~ . ~.: :\.!::;~ ,', . :\ .... '. " ' , . '. .. .. '.; 1Zmm TO "rnm WIDE HOLES IN ALnRNAlE BRICK COURSES i i 4 . ~ .. ~ II.._ _-'-_ _ _ _ _ _---j [5 . OF IIO'TTON OF PIT BY DoIPERVlOUS ""TER~ SUDi IS PUOOI£ cu.v OR ~ SHEEr DR LENI CElIENT CONCHm: OR sr..ausm SOIL SECTION A-B FRON JUNCTION ctWoI8ER NOTE:­ SEAUNG OF aaTTOJ,I HID SAND EHVEI.OPES TO BE PROYIDED WHERE MINIMUN SAFE IlISTANCE F'ROM THE WATER SOURCE CANNOT BE IoWNTAlHED PLAN Scale: 1:50 All dimensions in mm LEACH PITS WITH SAND ENVELOPE 18  How to operate and maintain a TPPF Latrine? Operation and maintenance of TPPF latrine pits and pitslocateu in water logged and is very simple but it is necessary to educate high sub-soil water areas, de-sludging of the users regarding its proper use and pits should be done c'arefully because the maintenance. sludge might not be completely safe and dry to handle due to travel of pathogens from the Diversion Of Flow From One Pit to pit in use to the pit to be desludged. After Another the pit is emptied, the pit cover should be placed in position and the joint made air Only one of the two pits is to be used at a tight. The humus collected has rich manure time. It is very important to completely seal value and is a good soil conditioner. The the entry to the pit which is not in use. This is humus from dry pits can be used directly done by blocking one of the branches of the either in the kitchen garden orthe fields, but drain or in the case ofa pipe, by blocking the from wet pits it can be used only when it is mouth of one pipe at the junction chamber sun dried. (see page 13). When water does not flow out of the pan, either there is chokage or the pit Dols and Dontls in use is full. If by rodding, the chokage is not removed, then the pit in use is full and the The following Do's and Dont's should be flow needs to be diverted to the second pit. explained to the users: For this, remove the cover orthe drain or junction chamber and take out the blockage Do's to allowthe flowto the pit not in use and block the flow to the pit which is full . Cover the * Keep a bucket full of water outside the drain or the junction chamber properly so latrine. that foul smell is not emitted. * Keep a2 litre can in the latrine filled with Removal And Disposal of Pit water for flushing. Sludge * Before use, pour a little quantity of water to wet the pan so that excreta slide When the filled pit is allowed to rest for a smoothly into the pit. minimum of one and a half years, the pit contents are completely digested and free of foul smell. The pit can then be safely * Flush the excreta after each use. emptied manually, without being hazardous to health, by the householder himself or * Pour a little quantity of water,say half a litre, in the squatting pan after urination. through the local authority or a private agency. However, in the case of combined 19 * The squatting pan should be cleaned daily * Do not throw sweepings, vegetable or with a soft broom or soft brush with a long fruit peelings, rags, cotton waste, and handle after sprinkling a small quantity of cleaning materials like corn cobs, mud water and detergent powder. balls, stone pieces, leaves etc. in the pan or the pits. * Use minimum quantity of water in washing . the pan and latrine floor. * Do not allow rain water, kitchen or bath waste water to enter the leach pits. * Wash hands, using soap or ash, after defecation at the assigned place. * Do not provide water tap in the latrine. * If any construction defect is observed * Do not throw lighted cigarette butts in the during the guarantee period, report the pan. matter to the local authority or the construction agency. * Do not desludge the pit before one and a half years of its being out of use. * When the pit in use is full, diver.t the flow to the second pit as discussed on page 19. * If the trap gets choked, rodding should be done from the pan side as well as from the rear side by means of a split bamboo stick, after removing the cover ofthe drain or junction chamber. * Care should be taken when desludging the pits located in water logged or high sub-soil water areas and in the case of combined pits, as the humus may not be safe for handling. DONT'S * Do not use both the pits at the same time. * Do not use more than 21itres of water for each flushing (if the waste is not flushed with 2 litres, pour more water at the specific spots for flushing the waste). * Do not use caustic soda or acid for cleaning the pan . 20  What should the supervisor check during construction? During construction, the supervisor should close to the pits, holes have not been check whether the following conditions have provided in the portion of lining facing been met: the foundation, and the leaching area has been increased suitably. * In the drawings 'H' is the depth of the pit below the invert level of connecting pipes * The minimum distance between the two or drain; not the total pit depth. pits is equal to the effective depth (depth of the pit below the invert of incoming * If the maximum ground · water level pipe or drain) of the pits. throughout the year remains 2 m or more below the pit bottom, and if the soil at * The pits have not been located in a site is fine (effective size 0.2 mm or depression where water may stagnate less), the pits have been located over the pits or in a drainage line which maintaining a minimum distance of 3 m allows the flow of rain water over the from the drinking water sources. If the pits. water table is higher, a minimum 10m distance be kepttominimizethe chances * The bottom of the leach pit has been left of pollution. in a natural condition except where it is necessary to seal lit to prevent pollution. * If the soil at the site is coarse (effective size more than 0.2 mm), a 500 mm thick * The RCC cover is of the thickness shown envelope offine sand of (0.2 mm effective in drawing on page 15 and has been size) has been provided all around the reinforced as per the design. pit, its bottom sealed, it is located at a minimum distance of 3 m if ground water * The top of the pit cover is about 50 mm table in any part of the year is 2 m or above the natural ground level and the more below the pit bottom. If the water earth fill is well compacted all around table is higher, a minimum distance of the cover sloping to avoid a step being 10m has been kept to prevent pollution formed. of drinking water sources. * The drain is 'U' shaped, cross­ * The pit size conforms to the geological sectionally and its inner surface is and hydrogeological conditions and the smooth. likely number of users,and adequate leaching area has been provided, if * Drains with benching have been properly necessary, by back filling for proper provided in the junction chamber infiltration of incoming liquid into the pits. (Drawing on page 16) to div~rt the flow In cases where the foundation is very to one of the two pits. 21 * A minimum gradient of 1: 15 has been * The covers over the pits, drains,and provided in the connecting drains or junction chamber have been placed pipes. properly. The mouth of the drains or pipes is * The pan and trap used are of a design projecting nearly 75 mm past the pit specified for pour flush and these have lining in the pits. been fixed properly so as to provide a 20 mm waterseal, and that the joint is * The flow has been restricted to one pit water tight and the top of the pan is flush by blocking the mouth of one of the drai ns with the latrine floor. or pipes. * No vent pipe has been provided. * The materials used are of the quality specified in the design, or relevant * A well ventilated superstructure has been stan dard specifi cati ons and th e provided to enable use of the latrine. workmanship is good. * All surplus materials have been removed * The specifications laid down have been and the site cleared and dressed. followed and the work has been finished neatly. * The users have been educated on the use and maintenance of PF latrines. * The floor surface is smooth and sloping slightly towards the pan. * The foot-rests have been fixed at the proper place and at an angle, as in the drawing. * 50 mm wide holes have been provided in the pit lining in alternate layers up to the invert of the pipe or drain, and the lining above is in solid brick work (no holes). If the soil is sandy, or if a sand envelope has been provided, or there are chances of damage by field rats, the width of the holes has been reduced-to 12 to 15 mm. If the foundation of the building is close to the pits, holes have not been provided in the portion of lining .facing the foundation. In cement concrete ring lining, rings belowthe invert of pipes or drains should have 50 mm circular holes staggered about 200 mm apart. 22 Annexes 23  Annex-1 Pour Flush Latrines with Dry Circular Leach Pits Size of Pits and Materials Required for 'C onstruction (for 5, 10 and 15 users) Assumptions: (a) 2 year desludging interval or solid storage volume (See page 5 under "storage period") (b) Soilds accumulation rate of 0.04m3/capita/day, assuming water is used for anal cleansing (See page 4 under "sludge accumulation rate") (c) Hydraulic loading 9.5Iitres/capita/day + 51itres per day for washing and cleaning squatting pan and latrine floor (See page 5 under "flow to the pit") (d) Ground water level throughout the year below the bottom of pit (See page 4 under "sludge accumulation rate") DRY PITS: SIZE IN MM 5 Users 10 .Users 15 Users Soli type Inflltra­ Pit Pit Width of Pit Pit Width Pit Pit Width tlon rate Dla Depth back Dia Depth of aack Dla Depth of back (l/m2/day) filling filling filling Clay; compact silty loams 10 900 650 750 '1000 1050 900 1200 1100 1450 Porous clay loams 20 900 650 100 1000 1050 150 1200 1100 350 Sandy loams 30 900 650 - 1000 1050 - 1200 1100 - Sand 50 900 650 - 1000 1050 - 1200 1100 - DRY PITS: MATERIALS REQUIRED FOR CONSTRUC1l0N Materials UnIt Quantity Materials Unit Quantity 5 Users 10 Users 15 Users 5 Users 10 Users 15 Users With Pipes And With Covered Brick Drain Bifurcation Chamber 1. Bricks Nos . 400 720 • 850 1 . Bricks Nos . 470 790 940 2 . Cement Bags 2 .53 3 .17 3.97 2. Cement Bags 2 .. 64 3 .28 4 . 14 3. Sand Cum 0 .43 0 .56 0.66 3. Sand Cum 0.45 0.58 0.69 4, Brick ballast Cum 0.23 0 .23 0.23 4. Brick ballast Cum 0.21 0 .21 0.21 5. Stone ballast Cum 0 . 15 0 .16 0.22 5. Stone bat!ast Cum 0.14 0 .15 0.21 6. M.S . bars Kg 8.00 8.50 12.00 6. M.S. bars Kg 8.00 8 .50 12.00 Note: 1. In soils with low infiltrative capacity, the pit size has been kept the same as in high infiltrative capacity soils, butthe infiltration area has been increased by providing backfilling all around the pits (see page 8 under "pits in soils with low infiltrative capacity"); 2. Depths of pit given above is the depth of pit below the invert of pipes or drains; the total depth of pits would be 300 mm more to allow free space (see page 4). 24  Annex-2 2lSmm lltCK CEWENT CON~ 1:2:4 OYER 7:lmm THICK calENT CONCRETE 1:6:12 .-ND TOP RNISHED SWOOTH BY COIENT PUNING FOOT R~ r - - - JtJNCTlON Q-W,IBER ElRICK WOfIK IN TOP a' PIT UMNC PlASTfRED CEIoIENT MORTAR I:. . 75mm DIA A.c. OR P.V.C. CEMENT IIQRTAR 1:8 NON PRESSURE PIPE R.C.C.sLA8 1:2:4 BRICK WORK IN CEMENT WORTAR 1:8 WITH HONEYCOMBING IN ALTERNATE BRICI< calENT CONCRETE 1:6:12 COURSES UP TO INVERT LEVEL Of PIPE OR DRAIN EARTH RUJNC :1:1 i ...... 225~ 225 ...... SECTION A-B-C ,11,1:i 0 -~,-.- . -.-.- . -.-.-~ t,1fj NOTE:­ i i i i THE SIZE OF" HOLES IN HONE"1t:OMBING SHOULD BE !IOrnm WIDE AND roll. HElGHT OF" BRICK COURSE. HOWEVER, IN SNIIDY SOIL OR WHERE THERE ARE Cl-WlCES OF" ~E BY Fl£lJ) RAlS OR WHERE SAND EI'Ml.OPE IS PROVIDED, WIDnI a' HOLES BE REDUCED TO 12 -TO l:lmm. OUTl£r TO BE OPENED ALTERNATU.Y DRY ' PIT * USERS D H T 5 900 650 50 10 1000 1050 50 15 1200 1100 60 * --0-­ 115 FOR nro YEAR sroRACE VOUJIoIE, LONG ' 1ERf,l INFlLTRATlON RATE OF" SOIL 30 UTERS PER SQ.IoIETtR PER DAY, EFEcTlVE SIZE Of FlORMA11ON SOIL O.2mm OR LESS AND GROUND Wot.TU T...a£ ·BELOW THE PIT BOTTOIoI Scole: 1:50 All dimensions in mm POUR FLUSH LATRINE WITH DRY CIRCULAR PITS 25  Annex-3 Pour Flush Latrines with Wet Circular Leach Pits Size of pits and Materials required for construction (for 5, 10 and 15 users) Assumptions: (a) 2 year desludging interval or solid storage volume (see page S under "storage period") (b) Soilds accumulation rate of 0.078m 3/capita/day, assuming water is used for anal cleansing (see page 4 under "sludge accumulation rate") (c) Hydraulic loading 9.Slitres/capita/day + Slitres per day for washing and cleaning squatting pan and latrine floor (see page S under "flow to the pit") (d) Ground water level is above the bottom of pit (see page 4 under "sludge accumulation rate") WET PITS: SIZE IN MM 5 Users 10 Users 15 Users Soli type Infllti'a­ Pit Pit Width of Pit Pit Width Pit Pit Width tlon rate Dla Depth back Dla Depth of Back Dla Depth of back (l/m2/day) fi 11/ ng filling filling Clay; compact silty loams 10 900 1250 100 1200 1400 450 1400 1550 700 Porous clay loams 20 900 1250 - 1200 1400 - 1400 1550 - Sandy loams 30 900 1250 - 1200 1400 - 1400 1550 - Sand 50 900 1250 - 1200 1400 - 1400 1550 - WET PITS: MATERIALS REQUIRED FOR CONSTRUCTION Materials Unit Quantity Materials Unit Quantity 5 Users 10 Users 15 Users 5 Users 10 Users 15 Users With Pipes And With Covered Brick Drain Bifurcation Chamber 1. Bricks Nos . 740 990 1200 1. Bricks Nos . 810 1080 1300 2. Cement Bags 3.08 4.32 5.62 2. Cement Bags 3.19 4.49 5.82 3. Sand Cum 0.57 0.75 0.91 3. Sand Cum 0.59 0.78 0.94 4. Brick ballast Cum 0.23 0.23 0.23 4. Brick ballast Cum 0.21 0.21 0.21 5. Stone ballast Cum 0.15 0.22 0.32 5. Stone ballast Cum 0.14 0.21 0.31 6. M.S. bars Kg 8.00 12.00 15.00 6. M.S. bars Kg 8.00 12.00 15.00 Note: 1. In soils with low infiltrative capacity, the pit size has been kept the same as in high infiltrative capacity soils, but the infiltration area has been increased by providing backfilling all around the pits (see page 8 under "pitsin soils with low infiltrative capacity "); 2. Depths of pit given above is the depth of pit below the invert of pipes or drains; the total depth of pits would be 300 mm more to allow free space (see page 4). 26  Annex-4 -25mm THICK CEMENT CONCRET'E 1:2:4 OVER 75mm THICK CfMEJIrT CONCRETE 1:11:12 AND TOP FINISHED SMOOTH BY COlEN!" PUNNING roor RESTS ,..----JUNCTlON CHof..MBER TOP OF PIT UNINC PlASTERED 75mm DIA A.C. OR P.V.C. N CEMEJIrT MORTAR 1:6 NON PRESSURE PIPE saUD BRICK Y«JRI( IN R.C.C.5I..AII 1:2:4 CEIoIo:NT I.4ORTM 1:6 • '. ' _'. '. f •••~ . ' .: II," ~i CEMENT CONCRETE 1:6:12 EAR1H FlWNG :z:! I BRICK WORK IN CENENT MORTAR 1:6 WrTH HONEYCOIIBlNG IN ALTERNATE BRICK i COURSES UP TO INVERT LEVEl. OF PIPE OR DRAIN i j2~ ~ NOTE:­ SECTION A-8-C THE SIZE OF HOLES IN HONEYCOll8lNC SHOULD BE ~mm WIDE AND FUll HEIGHT OF BRICK COURSE. HOWEVER. IN SANDY SOIL OR WHERE THERE ARE CHANCES OF IWoIAGE BY FIElD RATS OR WHERE SAND ENIon.OPE IS PROVIDED, WIDTH OF HOLES BE REDUCED TO 12 TO 15mm. WET PIT * USERS D H T c 5 900 1250 50 OUllET TO BE OPENED ALTERNAlELY ........-bl--115 -~ 10 1200 1400 60 ., 15 1400 1550 75 A -4- ::. I-+­ * FOR 'TWO YE',t,R STORAGE VOLUIIE, LONG TERM INFlLTRA1l0N RATE OF SOIL lO UTERS PER SQ.IoIETER PER DAY, ~ i i ErECTIVE SIZE OF FORIoIA1l0N SOIL O.2mm OR L£SS AND GROUND WA1£R TABL.£ ABOVE THE PIT BOTTOIol L-d---L 51. S' i!>! "I I -+­ -+- -jr­ :: - -...1-.- 115 Scole: 1:50 All dimensions in mm POUR FLUSH LATRINE WITH WET CIRCULAR PITS 27  Annex 5 Bill of Quantities for Pour Flush Latrine with Dry and Wet Circular Leach Pits A sslJ mptions:Thedesign shown in drawingson pages 25and 27j soil of effective size 0.2 mm orless, long term infiltration rate of soil 30 litres . per m2 per day and 2 year desludging interval. S.No. Item Unit Dry twin circular leach pits Wet twin circular leach pits Quantities: I Quantities: 5 10 15 5 10 15 Users Users Users Users Users Users I FOUNDATION AND PLINTH I , 1. Earthwork in excavation including disposal of excavated earth Cum 0.25 0.25 0.25 0.25 0.25 0.25 lead up to 50m and lift up to 1.5m, disposed earth to be levelled and neatly dressed . 2. Providin g and laying cement concrete in foundation, excluding the Cum 0.08 0.08 0.08 0.08 0.08 0.08 cost of centring and shuttering 1:6:12 (1 cement6 fine sand :12 brick ballast 40 mm nominal size) . 3. Brickwork with bricks of class designation 75 in foundation and Cum 0.21 0.21 0.21 0.21 0.21 0.21 I plinth in cement mortar 1:6 (1 cement : 6 fine sand) . 4. 25 mm thick with 12.5 mm nominal size stone aggregate Sqm 0.68 0.68 0.68 0.68 0.68 0.68 cement concrete flooring 1:2:4 (1 cement2 coarse sand:4 graded stone aggregate) finished with a floating coat of neat cement including cement slurry, rounding of edges and strips I etc.over 75 mm thick with 40 mm nominal size brick ballast I I cement concrete 1 :6:12 (1 cement6 fine sand:12 brick ballast) . 5. Supplying and fixing squatting pan , trap and footrests. Set 1 1 1 I 1 1 1 : 28  Annex 5 S.No. Item Unit Dry twin circular leach pits Wet twin circular leach pits Qua ntitles: I Quantities: 5 10 15 5 10 15 Users Users Users Users Users Users I INTERCONNECTION BETWEEN PITS AND TRAP ALTERNATIVE-1 Pipes With Bifurcation Chamber I 1. Earthwork in excavation including disposal Cum 0.40 0.40 0.45 0.40 0.45 0.51 of excavated earth lead upto 50 m and lift upto 1 .5 m , disposed earth to be levelled and neatly dressed . 2. Supply, lay and joint 75mm dia. A.C. pipe including jointing M 3.0 3.0 3.5 3.0 3.5 4.0 material etc . complete. 3. Providing and laying cement concrete in foundation and plinth Cum 0.02 0.02 0.02 0.02 0.02 0.02 excluding the cost of centring and shuttering 1 :6: 12 (1 cement: 6 fine sand: 12brick ballast 40 mm nominal size) . 4. Brickwork with bricks of class designation 75 in foundation and Cum 0.03 0.03 0.03 0.03 0.03 0.03 plinth in cement mortar 1 :6 (1 cement:6 fine sand). 5. 12 mm cement plaster of mix 1 A (1 cementA coarse sand) Sqm 0.15 0.15 0.15 0.15 0.15 0.15 finished with cement punning . 6. Providing and laying cement concrete 1 :2A(1 cement:2 coarse Cum 0.002 0.002 0.002 0.002 0.002 0.002 sand : 4 stone ballast 20 mm nominal size) in drains and benching, excluding the cost of centring & shuttering but I including rendering the surface smooth with cement. I - - - - - - 29  Annex 5 S.No. Item Unit Dry twin circular leach pits Wet twin circular leach pits Quantities: Qua ntltles: 5 10 15 5 10 15 I I I Users Users . Users Users Users Users I 7. Reinforced cement concrete work 1 :2:4 (1 cement2 coarse Cum 0.005 0.005 0.005 I 0.005 0.005 0.005 sand:4 graded stone aggregate 20 mm nominal size) excluding I I I cost of centring . shuttering and reinforcement. 8. Reinforcementfor R.C.C. work including bending. binding and Kg 0.60 0.60 0.60 0.60 0.60 0.60 I placing in position complete. ! I ALTERNATIVE -2 I I Covered Brick Drains (3 m for 5 & 10 users and 3.5 m for 15 users of dry pits and 3 m for I 5 users. 3.5 m for 10 users and 4 m for 15 users of wet pits) 1. Earthwork in excavation including disposal of excavated Cum 0.20 0.20 0.23 0.20 0.23 0.26 earth lead upto 50 m and lift upto 1.5 m . disposed earth I to be levelled and neatly dressed. I 2. Brickwork with bricks of class designation 75 in foundation Cum 0.12 0.12 0.14 0.12 0.14 0.16 and plinth in cement mortar 1 :6 (1 cement6 fine sand). I I 3. Brickwork with bricks of class designation 75 in foundation Cum 0.06 0.06 0.07 I 0.06 0.07 0.08 I I and plinth in mud mortar or cement mortar 1 :12. I 4. Providing and laying cement concrete 1:3:6 (1 cement:3 Cum 0.003 0.003 0.004 I 0.003 0.004 0.004 I coarse sand:6 graded stone aggregate 20mm nominal size) I I in haunches of drain excluding the cost of centring I , and shuttering. , I 30  Annex 5 S.No. Item Unit Dry twin circular leach pits Wet twin circular leach pits Quantities: Quantities: 5 10 15 5 10 15 Users Users Users Users Users Users 5. 12 mm cement plaster of mix 1 :4 (1 cement:4 coarse sand) Sqm 0.86 0.86 1.00 0.86 1.00 1.14 I finished with cement punning. 6. Making bed of drain of 'U' cross sectional shape as per drawing Job Job Job , Job Job Job and finished smooth with cement punning. I LEACH PITS 1. Earth work in excavation including disposal of excavated , earth lead upto 50 m, disposed earth to be levelled and neatly dressed. Upto 1.5 m below ground level Cum 2.40 3.93 5.35 3.62 5.59 7.13 1.5 m to 3.0 m below ground level Cum - - - 0.23 0.89 1.83 2 Brickwork with bricks of class designation 75 in foundation Cum 0.33 0.36 0.43 0.33 0.43 0.49 and plinth in cement mortar 1 :6 (1 cement:6 fine sand). 3. Honeycomb brick work 10/11.4 cm thick with bricks of class Cum 0.48 0.85 1.05 0.92 1.33 1.70 designation 75 in cement mortar 1 :6 (1 cement:6 find sand). 4. 12 mm cement plaster of mix 1 :6 (1 cement:6 fine sand) over Sqm 0.73 0.81 0.95 0.73 0.95 1.09 the top of pit lining. 31  Annex 5 S.No. Item Unit Dry twin circular leach pits Wet twin circular leach pits Quantities: Quantities: 5 10 15 5 10 15 Users Users Users UIers Users Users 5. Reinforced cement concrete work 1:2:4 (1 cement:2 coarse Cum 0.10 0.12 0.19 0.10 0.19 0.31 sand:4 graded stone aggregate 20 mm nominal size) excluding cost of centring, shuttering and reinforcement. 6. Reinforcementfor R.C.C. work including bending, binding and Kg 7.0 7.8 11.5 7.0 11.5 14.5 placing in position complete. - - - ­ 32 Design & TypesetatGRAFIX, 11/1, Gurudwara Road, Bhogal, New Delhl-110014.